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January 27, 2006

Exercise may counter mental decline from HRT

by Sam Savage

NEW YORK (Reuters Health) - Regular exercise may prevent
the mental decline associated with the long-term use of hormone
replacement therapy (HRT), preliminary research suggests.

In a study of 54 postmenopausal women, investigators found
that long-term HRT use -- more than 10 years -- was linked with
poorer scores on a standard test of mental acuity. However,
physical fitness appeared to counter this effect, according to
findings published in the journal Neurobiology of Aging.

While recent research in animals and humans has suggested
that short-term estrogen replacement may help thwart
age-related mental decline, long-term HRT use may have the
opposite effect.

In the new study, researchers at the University of Illinois
at Urbana-Champaign looked at whether women's fitness levels
made a difference in the brain effects of HRT.

Dr. Kirk I. Erickson and his colleagues collected
information on HRT use and used MRI scans to measure tissue
volume in several key brain areas. The women also took a
standard test of memory and mental agility, as well as a
treadmill test to gauge their cardiovascular fitness.

Overall, the researchers found that short-term HRT use --
up to 10 years -- was associated with greater brain tissue
volume and better test scores. And higher fitness levels
appeared to "augment" this benefit, they write.

Longer-term HRT use, in contrast, was linked to lower brain
tissue volume and poorer test scores. However, physical fitness
seemed to offset this effect, according to the researchers.

"It may be that a combination of HRT and exercise boosts
both cognition and brain structure of older women," study
co-author Dr. Arthur F. Kramer said in a statement.

It's not clear why exercise and short-term, but not
long-range, HRT may be beneficial to the aging brain. Both
estrogen and physical activity, the study authors note,
stimulate a substance called brain-derived neurotropic factor,
which is involved in the production of brain cells and blood
vessels.

Whatever the reasons for the findings, Erickson and his
colleagues conclude, they do demonstrate that brain atrophy "is
not an inevitable consequence of aging," and there may be
several ways - such as exercise, a healthful diet or staying
mentally active -- that can slow or stop the process.